Wider grip is a looot easier bc you shorten range of motion. With narrow grip you'll get so deep that your tricpes will be in a stretched position and it's super hard to push having such a deep elbow flexion. Also when going for a narrower grip and assuming you wanna have perfectly straight form, you'll have to incline your body more (your body will be more horizontally and less vertically) which due to increased lever forces makes things a looot harder! I'd say the more inclined you are, the more upper chest is involved, but again, you put yourself in a very - aesthetically beautiful but - mechanically disadvantageous position, hence many people do banana form 🍌